Ferroelectric material, and electronic device including the same

ABSTRACT

Provided are a ferroelectric material and an electronic device including same, the ferroelectric material including: a first domain including a first polarization layer which is polarized in a first direction and a first spacer layer disposed adjacent to the first polarization layer; a second domain including a second polarization layer which is polarized in a second direction distinct from the first direction and a second spacer layer disposed adjacent to the second polarization layer; and a structural layer, which is disposed at a domain wall between the first domain and the second domain, and belongs to/has atoms arranged according to a Pbcn space group.

CROSS-REFERENCE TO RELATED APPLICATION

This application is based on and claims priority under 35 U.S.C. §119 toKorean Patent Application No. 10-2021-0125248, filed on Sep. 17, 2021,in the Korean Intellectual Property Office, the disclosure of which isincorporated by reference herein in its entirety.

BACKGROUND

Some example embodiments relate to a ferroelectric material, and/or anelectronic device including the same.

Semiconductor devices such as memory devices and/or transistors are usedin various household and industrial devices. According to the highperformance of household and industrial devices, high integration and/orminiaturization of semiconductor devices are progressing.

Therefore, various forms of semiconductor devices have been proposed.For example, a semiconductor device employing a dielectric layerincluding a ferroelectric material has been proposed. Domain inversionmay occur in a ferroelectric material, and thus, using such properties,ferroelectric materials are applicable to various semiconductor devices.As ferroelectric materials, a perovskite-based ferroelectric materialand a fluorite-based ferroelectric material are known.

SUMMARY

A ferroelectric material having a fluorite structure is low in domaininversion rate since the magnitude of the energy barrier that must becrossed in domain inversion is high. For example, in existingferroelectric materials having the fluorite structure, the magnitude ofthe energy barrier when domain inversion occurs is two times or morecompared to that of perovskite-based ferroelectric materials. Therefore,there is a need or a desire for a novel fluorite-based ferroelectricmaterial with increased domain inversion speed due to a reduction in themagnitude of the energy barrier when domain inversion occurs, comparedto the fluorite-based ferroelectric material of the related art.

One or more example embodiments include a ferroelectric material, whichincludes a structural layer having a novel symmetric structure, andthus, the magnitude of an energy barrier when domain inversion occurs isreduced/significantly reduced.

One or more example embodiments include an electronic device includingthe ferroelectric material.

Additional aspects will be set forth in part in the description whichfollows and, in part, will be apparent from the description, or may belearned by practice of various example embodiments.

According to one or more example embodiments, provided is aferroelectric material including a first domain including a firstpolarization layer which is configured to be polarized in a firstdirection and a spacer layer adjacent to the first polarization layer, asecond domain including a second polarization layer which is configuredto be polarized in a second direction distinct from the first directionand a spacer layer adjacent to the second polarization layer, and astructural layer, which is at a domain wall between the first domain andthe second domain.

According to one or more example embodiments, provided is aferroelectric material including a first domain including a firstpolarization layer which is configured to be polarized in a firstdirection and a spacer layer adjacent to the first polarization layer, asecond domain including a second polarization layer which is configuredto be polarized in a second direction distinct from the first directionand a spacer layer adjacent to the second polarization layer, and astructural layer, which is at a domain wall between the first domain andthe second domain, the structural layer being arranged (e.g. havingatoms arranged) according to a Pbcn space group.

According to one or more example embodiments, provided is an electronicdevice including the ferroelectric material described above.

According to one or more example embodiments, provided is aferroelectric material including a first domain including a firstpolarization layer configured to be polarized in a first direction and aspacer layer adjacent to the first polarization layer, and a structurallayer at a domain wall between the first domain and a second domain, thestructural layer having metal atoms and oxygen atoms, the metal atomsand the oxygen atoms arranged as a Pbcn space group.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other aspects, features, and advantages of certainembodiments of the disclosure will be more apparent from the followingdescription taken in conjunction with the accompanying drawings, inwhich:

FIG. 1 is a schematic view showing a structure of a ferroelectricmaterial according to some example embodiments;

FIG. 2 is a schematic view showing a structure of a ferroelectricmaterial and propagation of a domain wall, according to some exampleembodiments, in which view (a) is a schematic view showing a structurebefore propagation of the domain wall, view (b) is a schematic viewshowing a structure of the ferroelectric material during propagation ofthe domain wall, and view (c) is a schematic view showing a structure ofthe ferromagnetic material after propagation of the domain wall;

FIG. 3 shows schematic views (a) to (h) showing orthorhombic crystalstructures of ferroelectric materials according to embodiments;

FIG. 4 is a schematic view showing chirality of the structure of aferroelectric material according to some example embodiments;

FIG. 5 shows schematic views (a) to (c) of orthorhombic crystalstructures, which belong to/have atoms arranged in a Pbcn space groupand are disposed at domain walls of a ferroelectric material accordingto some example embodiments;

FIG. 6 shows schematic views (a) to (c) of orthorhombic crystalstructures, which belong to/have atoms arranged in a Pbcn space groupand are disposed in a bulk state domain of a ferroelectric materialaccording to some example embodiments;

FIG. 7A is a graph showing results of calculation of changes in energybarrier in a ferroelectric material including a domain which belongs aPbcn space group, and changes in energy barrier according to strainmagnitude in a domain inversion from the domain which belongs to thePbcn space group to a domain which belongs to a P42/nmc space group;

FIG. 7B is a graph showing an energy barrier with respect to strainmagnitude when domain inversion (e.g., switching energy) occurs, andrelative stability of the domain which belongs to the Pbcn space groupto the domain which belongs to the P42/nmc space group;

FIGS. 8 and 9 are schematic views showing field-effect transistors(FETs) according to some example embodiments;

FIG. 10 is a schematic view showing a semiconductor device according tosome example embodiments;

FIG. 11 is a schematic view showing a structure of a Fin-FET as asemiconductor device according to some example embodiments;

FIG. 12 is a schematic view showing a structure of a gate-all-around-FETas a semiconductor device according to some example embodiments;

FIG. 13 is a schematic view showing a capacitor according to someexample embodiments;

FIG. 14 is a schematic view showing a structure of a semiconductordevice according to another embodiment, e.g., a connection structure ofa capacitor and an FET;

FIG. 15 is a schematic cross-sectional view illustrating a structure ofan electronic device according to some example embodiments;

FIG. 16 is a schematic cross-sectional view showing a gate structure ofthe electronic device shown in FIG. 15 ;

FIG. 17 is a schematic view of an electronic device according to someexample embodiments; and

FIG. 18 is a schematic illustration of an electronic device, accordingto some example embodiments.

DETAILED DESCRIPTION OF VARIOUS EXAMPLE EMBODIMENTS

Reference will now be made in detail to various embodiments, examples ofwhich are illustrated in the accompanying drawings, wherein likereference numerals refer to like elements throughout. In this regard,example embodiments may have different forms and should not be construedas being limited to the descriptions set forth herein. Accordingly,example embodiments are merely described below, by referring to thefigures, to explain aspects. As used herein, the term “and/or” includesany and all combinations of one or more of the associated listed items.Expressions such as “at least one of,” when preceding a list ofelements, modify the entire list of elements and do not modify theindividual elements of the list.

Some example embodiments will now be described more fully with referenceto the accompanying drawings, in which example embodiments are shown.Various example embodiments may, however, be embodied in many differentforms, should not be construed as being limited to example embodimentsset forth herein, and should be construed as including allmodifications, equivalents, and alternatives within the scope of exampleembodiments; rather, various embodiments are provided so that thisdisclosure will be thorough and complete, and will fully convey theeffects and features of example embodiments and ways to implement thedisclosure to those of ordinary skill in the art.

The terminology used herein is for the purpose of describing particularembodiments only and is not intended to be limiting of some exampleembodiments. As used herein, the singular forms “a”, “an” and “the” areintended to include the plural forms as well, unless the context clearlyindicates otherwise. It will be further understood that the terms“comprises” and/or “comprising,” when used in this specification,specify the presence of stated features, integers, steps, operations,elements, and/or components, but do not preclude the presence oraddition of one or more other features, integers, steps, operations,elements, components, and/or groups thereof. As used herein, the slash“/” or the term “and/or” includes any and all combinations of one ormore of the associated listed items.

In the drawings, the size or thickness of each layer, region, or elementare arbitrarily exaggerated or reduced for better understanding or easeof description, and thus some example embodiments is not limitedthereto. Throughout the written description and drawings, like referencenumbers and labels will be used to denote like or similar elements. Itwill also be understood that when an element such as a layer, a film, aregion, or a component is referred to as being “on” another layer orelement, it can be “directly on” the other layer or element, orintervening layers, regions, or components may also be present. Althoughthe terms “first”, “second”, etc., may be used herein to describevarious elements, components, regions, and/or layers, these elements,components, regions, and/or layers should not be limited by these terms.These terms are used only to distinguish one component from another, notfor purposes of limitation. In the following description and drawings,constituent elements having substantially the same functionalconstitutions are assigned like reference numerals, and overlappingdescriptions will be omitted.

As used herein, the term “domain wall (DW)”, which is a region among aplurality of domains, means or refers to or corresponds to a regionincluding, for example, zero unit cells to five unit cells.

As used herein, the expression “arranged at a domain wall” or “arrangedat the domain wall” means or refers to or corresponds to an arrangementto include part or all of the domain wall.

Hereinafter, example embodiments of a ferroelectric material and/or anelectronic device including the same will be described in greaterdetail.

A ferroelectric material according to one or more example embodimentsincludes: a first domain including a first polarization layer, which ispolarized in or is configured to be polarized a first direction, and aspacer layer disposed adjacent to the first polarization layer; a seconddomain including a second polarization layer, which is polarized in oris configured to be polarized in a second direction distinct from thefirst direction, and a spacer layer disposed adjacent to the secondpolarization layer; and a structural layer, which is disposed at adomain wall between the first domain and the second domain and belongsto a Pbcn space group. As used herein, when a material is described asbelonging to a specific space group, this is to be construed as theatomic structure of the material has atoms arranged according to theparticular space group.

In the ferroelectric material including, at the domain wall, thestructural layer which belongs to/has atoms arranged according to thePbcn space group, when an external electric field is applied to theferroelectric material, while a symmetric structure of the structurallayer at the domain wall between the first domain and the second domainchanges according to a direction in which the electric field is applied,a change in the direction of polarization of the structural layer mayoccur. Due to the change in polarization direction of the structurallayer, a domain inversion occurs. Consequently, the domain wallpropagates. Due to repeated propagations of the domain wall, apolarization direction of the first domain and/or second domain changesas a whole. Due to the arrangement of the structural layer, whichbelongs to or has atoms arranged according to the Pbcn space group, atthe domain wall of the ferroelectric material, the magnitude of theenergy barrier when domain inversion occurs is reduced. Accordingly, thepropagation speed at the domain wall in the ferroelectric materialincreases, and the operation speed of an electronic device including theferroelectric material becomes faster.

FIG. 1 is a schematic view showing a domain wall (DW) of a ferroelectricmaterial according to various example embodiments.

Referring to FIG. 1 , a ferroelectric material according to variousexample embodiments includes a first domain D1 including a firstpolarization layer PL1, which is polarized in a first direction, and aspacer layer SL disposed adjacent to the first polarization layer PL1,and a second domain D2 including a second polarization layer PL2, whichis polarized in a second direction distinct from the first direction,and a spacer layer SL disposed adjacent to the second polarization layerPL2. A structural layer STL, which belongs to or has atoms arrangedaccording to a Pbcn space group, is arranged at a domain wall DW betweenthe first domain D1 and the second domain D2. The structural layer STLincluded in the ferroelectric material may have, for example, anorthorhombic crystal structure. Accordingly, the structural layer STLincluded in the ferroelectric material may include an orthorhombiccrystalline phase which belongs to/has atoms arranged according to thePbcn space group. As the structural layer STL arranged at the domainwall of the ferroelectric material includes an orthorhombic crystallinephase which belongs to a Pbcn space group, the magnitude of the energybarrier when domain inversion or a polarization direction change occursmay be reduced.

Referring to FIG. 1 , the structural layer STL may include, for example,the first polarization layer PL1 and the second polarization layer PL2.The first polarization layer PL1 and the second polarization layer PL2may be sequentially arranged along one direction. The first polarizationlayer PL1 and the second polarization layer PL2 may be arranged tocontact, e.g. to directly contact each other. For example, the spacerlayer SL may not be present between the first polarization layer PL1 andthe second polarization layer PL2. As the structural layer STL includedin the ferroelectric material has such a structure, the magnitude of theenergy barrier when domain inversion or polarization direction changeoccurs may reduce.

Referring to FIG. 2 , for example, when an external electric field isapplied to the ferroelectric material having a structure of (a) in FIG.2 , the symmetric structure of the second polarization layer (PL2)included in the structural layer (STL) changes, and thus the secondpolarization layer PL2 is converted into the spacer layer SL, and aferroelectric state having a structure of (b) of FIG. 2 is reached.Subsequently, the symmetrical structure of the spacer layer SL includedin the structure layer STL changes, and thus the spacer layer SL isadditionally converted into the first polarization layer PL1, and thusthe structure of a ferroelectric material is switched to a structure (c)of FIG. 2 . Accordingly, while the symmetrical structure of thestructural layer arranged at the domain wall changes, a polarizationdirection change occurs in the second polarization layer PL2 and/or thespacer layer SL adjacent to the second polarization layer PL2. Due tothe polarization direction change in the structural layer at the domainwall, domain inversion occurs and the domain wall propagates. Forexample, domain propagation occurs (e.g. horizontally in FIG. 1 ). Forexample, while the structural layer goes through a process of forming atetragonal crystalline phase, which belongs to or has atoms arrangedaccording to P4₂/nmc space group, from an orthorhombic crystallinephase, which belongs to or has atoms arranged according to a Pbcn spacegroup, and then again forming the orthorhombic crystalline phase, whichbelongs to or has atoms arranged according to the Pbcn space group, thedomain wall sequentially propagates. Due to the inclusion of theorthorhombic crystalline phase, which belongs to the Pbcn space group,in the structural layer STL arranged at the domain wall DW, the energybarrier when domain inversion occurs reduces, and thus, the domainpropagation speed may increase. For example, the operation speed of anelectronic device including the ferroelectric material may increase.

The ferroelectric material of some example embodiments may be afluorite-based ferroelectric material including a fluorite-typecompound. Alternatively or additionally, the fluorite-basedferroelectric material may have a fluorite-type structure, e.g.,fluorite structure. As used herein, a fluorite-based structure orfluorite-type compound is a compound which may or may not includefluorine, and has an atomic structure such as MX₂. Here, M is a metal,and has atoms arranged according to a face-centered cubic structure.Accordingly, this is distinct from a perovskite-based ferroelectricmaterial having a perovskite structure. The fluorite-based structure orfluorite-type compound may belong to Pca2₁, P4₂/nmc, P2₁/c, Pmn2₁, R3,or R3m space group.

FIG. 3 shows detailed structures of a first polarization layer PL1, asecond polarization layer PL2, and a spacer layer SL included in aferroelectric material a fluorite structure, according to some exampleembodiments. In FIG. 3 , { } indicates right-handed chirality, and []indicates left-handed chirality. In FIG. 3 , Mxy indicates a mirrorimage relationship. In FIG. 3 , Ry(Π) indicates a relationship ofrotation by 180 degrees/ Π radians with respect to y-axis.

In FIG. 3 , structure (a) is an image, in a (100) plane direction, of aferroelectric unit cell which has a fluorite structure and includes aspacer layer SL and a first polarization layer PL1. The firstpolarization layer PL1 is a region which corresponds to the right halfof the unit cell and is defined by two large metal ions and four smalloxygen ions between them. More specifically, the first polarizationlayer PL1 is a region including four 1/8 metal ions arranged atright-side corners, four 1/4 metal ions arranged on the front side, therear side, the top side, and the bottom side, and one 1/2 metal ionarranged on the right side. Therefore, the first polarization layer PL1includes four oxygen ions and two metal ions. In addition, in the firstpolarization layer PL1, the four oxygen ions and the two metal ions arearranged to have non-symmetry in a polar C-axis direction, and the firstdirection is one of two directions parallel to the polar C-axisdirection. In the first polarization layer PL1, for example, the fouroxygen ions may be arranged to deviate from a center plane between thetwo metal ions. Accordingly, the first polarization layer PL1 may havepolarization, and may affect polarization of the ferroelectric material.The polarization layer PL may have a “u” form (up form) or a “d” form(down form) according to a polarization direction ((-)→(+)) dependent onthe locations of the oxygen ions and metal ions of the polarizationlayer. For example, the first polarization layer PL1, which is polarizedin a first direction, may have a “u” form. Accordingly, the firstdirection may be denoted by ↑ (an up arrow), and may be denoted by u in(a) to (h) of FIG. 3 . The first polarization layer PL1 mayalternatively be referred to as a non-symmetric segment.

In FIG. 3 , structure (b) is an image, in a (100) plane direction, of aferroelectric unit cell which has a fluorite structure and includes aspacer layer SL and a second polarization layer PL2. The secondpolarization layer PL2 is a region which corresponds to the right halfof the unit cell and is defined by two large metal ions and four smalloxygen ions between them. More specifically, the first polarizationlayer PL2 is a region including four 1/8 metal ions arranged atleft-side corners, four 1/4 metal ions arranged on the front side, therear side, the top side, and the bottom side, and one 1/2 metal ionarranged on the right side. Therefore, the second polarization layer PL2includes four oxygen ions and two metal ions. In addition, in the secondpolarization layer PL2, the four oxygen ions and the two metal ions arearranged to have non-symmetry in a polar C-axis direction, and thesecond direction is a direction opposite to the first direction which isparallel to the polar C-axis direction. For example, in the secondpolarization layer PL2, the four oxygen ions may be arranged to deviatefrom the center plane between the two metal ions. Accordingly, thesecond polarization layer (PL2) may affect polarization of theferroelectric material. The polarization layer PL may have a “u” form ora “d” form according to a polarization direction ((-)→(+)) dependent onthe locations of the oxygen ions and metal ions of the polarizationlayer. For example, the second polarization layer PL2, which ispolarized in a second direction, may have a “d” form. Accordingly, thesecond direction may be denoted by t, and may be denoted by d in (a) to(h) of FIG. 3 . The second polarization layer PL1 may alternatively bereferred to as a non-symmetric segment.

Referring to structures (a) and (b) of FIG. 3 , the spacer layer (SL) isa region which corresponds to the left half of the unit cell and isdefined by two large metal ions and four small oxygen ions between them.More specifically, the spacer layer SL is a region including four 1/8metal ions arranged at left-side corners, four 1/4 metal ions arrangedon the front side, the rear side, the top side, and the bottom side, andone 1/2 metal ion arranged on the left side. Therefore, the spacer layerSL includes four oxygen ions and two metal ions. In addition, in thespacer layer SL, four oxygen ions and two metal ions are arranged tohave symmetry in the polar C-axis direction. For example, in the spacerlayer SL, the four oxygen ions may be arranged on the center planebetween the two metal ions. Accordingly, the spacer layer SL may notaffect polarization of the ferroelectric material. The spacer layer isindicated by s in (a) to (h) of FIG. 3 . The spacer layer SL may also bereferred to differently as a symmetric segment.

In FIG. 3 , structure (b) corresponds to a structure that structure (a)rotated by 180 degrees with respect to y-axis. Accordingly, structure(b) of FIG. 3 has the same chirality as structure (a) of FIG. 3 . InFIG. 3 , structure (e) corresponds to a mirror image structure ofstructure (a) of FIG. 3 . Accordingly, structure (e) of FIG. 3 hasdifferent chirality from structure (a) of FIG. 3 . In FIG. 3 , structure(f) corresponds to a mirror image structure of structure (b) of FIG. 3 .Accordingly, structure (f) of FIG. 3 has different chirality fromstructure (b) of FIG. 3 . In FIG. 3 , structure (c) corresponds to astructure in which a first polarization layer PL1 and a spacer layer SLare arranged at positions opposite to those of structure (a) of FIG. 1 .In FIG. 3 , structure (d) corresponds to a structure that structure (c)rotated by 180 degrees with respect to y-axis. Accordingly, structure(d) of FIG. 3 has the same chirality as structure (c) of FIG. 3 . InFIG. 3 , structure (g) corresponds to a mirror image structure ofstructure (c) of FIG. 3 . Accordingly, structure (g) of FIG. 3 hasdifferent chirality from structure (c) of FIG. 3 . In FIG. 3 , structure(h) corresponds to a mirror image structure of structure (d) of FIG. 3 .Accordingly, structure (h) of FIG. 3 has different chirality fromstructure (d) of FIG. 3 .

Referring to FIGS. 1 to 4 , the first domain D1 may include a pluralityof first polarization layers PL1 and a plurality of spacer layers SLarranged between the plurality of first polarization layers PL1, and thesecond domain D2 may include a plurality of second polarization layersPL2 and a plurality of spacer layers SL arranged between the pluralityof second polarization layers PL2. For example, the first domain D1 mayhave a structure in which a plurality of first polarization layers PL1and a plurality of spacer layers SL are alternately arranged along onedirection. The direction in which the plurality of first polarizationlayers PL1 and the plurality of spacer layers SL are alternatelyarranged may be, for example, a direction oppose to /orthogonal to thedomain wall DW. For example, the second domain D2 may have a structurein which a plurality of second polarization layers PL2 and a pluralityof spacer layers SL are alternately arranged along one direction. Thedirection in which the plurality of second polarization layers PL2 andthe plurality of spacer layers SL are alternately arranged may be, forexample, a direction oppose to/orthogonal to the domain wall DW. Theplurality of first polarization layers PL1 included in the first domainD1 may be polarized in the same first direction. For example, theplurality of first polarization layers may be denoted by ↑ in FIGS. 1,2, and 4 , and by u in (a) to (h) of FIG. 3 . The plurality of secondpolarization layers PL2 included in the second domain D2 may polarize inthe same second direction. For example, the plurality of secondpolarization layers PL2 may be denoted by ↓ in FIGS. 1, 2, and 4 , andby d in (a) to (h) of FIG. 3 .

Referring to FIG. 4 , first polarization layers PL1 and secondpolarization layers PL2, which are included in the structural layer STL,may have, for example, the same chirality. For example, the firstpolarization layers PL1 are polarized in the first direction, and thus,are denoted by u, and the second polarization layers PL2 are polarizedin the second direction, and thus, are denoted by d. However, the firstpolarization layers PL1 and the second polarization layers PL2 have thesame right-handed chirality, and thus, may be denoted by { }. Forexample, the first polarization layers PL1 and the second polarizationlayers PL2 are denoted by {u} and {d}, respectively. Thus, mirror imagesof the steric atomic arrangements of the first polarization layers PL1and the second polarization layers PL2 may be superimposable. Since thefirst polarization layers PL1 and the second polarization layers PL2have the same chirality, the magnitude of the energy barrier when domaininversion and/or polarization direction switching occurs may be reduced.

FIG. 5 shows schematic views (a) to (c) of fluorite crystal structures,which are included in a structural layer locally arranged at domainwalls and belong to/having atoms arranged according to a Pbcn spacegroup, and FIG. 6 shows schematic views (a) to (c) of fluorite crystalstructures in a bulk state domain, which belong to/has atoms arrangedaccording to a Pbcn space group. In FIGS. 5 and 6 , (a) shows fluoritecrystal structures along a (010) direction. In FIGS. 5 and 6 , (b) showsfluorite crystal structures along a (001) direction. In FIGS. 5 and 6 ,(c) shows fluorite crystal structures along a (100) direction.

As shown in (a) to (c) of FIGS. 5 and 6 , the crystal structure of acrystalline phase, which belong to/has atoms arranged according to aPbcn space group, in the structural layer locally disposed at the domainwalls differs from the crystal structure of a crystal phase whichbelongs to a Pbcn space group disposed in a bulk state domain.Accordingly, in the ferroelectric material including the structurallayer, which belongs to a Pbcn space group, at the domain walls, themagnitude of an energy barrier when domain conversion or polarizationdirection switching occurs may reduce.

FIG. 7A shows results of calculation of changes in energy barrier in aferroelectric material including a domain which belongs a Pbcn spacegroup, and changes in energy barrier according to strain magnitude, whendomain inversion occurs from the domain which belongs to the Pbcn spacegroup to a domain which belongs to a P42/nmc space group; FIG. 7B showsenergy barrier with respect to strain magnitude when domain inversion(i.e., switching energy) occurs, and relative stability of the domainwhich belongs to the Pbcn space group to the domain which belongs to theP4₂/nmc space group.

As shown in FIGS. 7A and 7B, when 0% strain was applied to theferroelectric material, the energy barrier when domain inversionoccurred from the domain which belongs to a Pbcn space group to thedomain which belongs to a P4₂/nmc space group was 73 meV. Meanwhile,when 0.3% strain was applied to the ferroelectric material, the energybarrier when domain inversion occurred from the domain which belongs toa Pbcn space group to the domain which belongs to a P4₂/nmc space groupwas 36 meV. Accordingly, as the strain applied to the ferroelectricmaterial increased, the energy barrier when domain inversion occurredfrom the domain belonging to the Pbcn space group to the domainbelonging to the P4₂/nmc space group was reduced by 51%. Alternativelyor additionally, as shown in FIG. 7B, relative stability of thecrystalline phase which belongs to the Pbcn space group with respect tothe crystalline phase which belongs to the P4₂/nmc space groupsignificantly increased. For example, it can be shown that in theferroelectric material locally including the structural layer, whichbelongs to the Pbcn space group, at the domain walls between the domainswhich belong to the P4₂/nmc space group, the energy barrier when domaininversion occurred significantly reduced, compared to existingfluorite-based ferroelectric materials of the related art, and theenergy barrier when domain inversion occurred further reduced as astrain was applied to the ferroelectric material.

Referring to FIGS. 7A to 7B, a strain applied to the structural layermay be, for example, about -1 % to about 1 %, or about -0.5% to about0.5%. The strain applied to the structural layer STL may be, forexample, about -1% to about -0.1%, or about -0.5% to about -0.1%. Thestrain applied to the structural layer STL may be, for example, about0.1% to about 1%, or about 0.1% to about 0.5%. When the strain appliedto the structural layer is within these ranges, the magnitude of theenergy barrier when domain inversion or polarization direction switchingoccurs may be reduced. The strain applied to the structural layer STLmay be, for example, tensile strain. The strain applied to thestructural layer STL may be implemented using various methods, forexample, one or more of heat treatment such as annealing, doping withdopants, and/or the like. For example, by doping a ferroelectricmaterial with dopants having an atomic size different from atomsconstituting the ferroelectric material, a strain may be applied to thestructural layer. Alternatively or additionally, by arranging andannealing a metal electrode layer on a dielectric layer including theferroelectric compound and annealing a metal electrode layer, a strainmay be applied to the structural layer.

Referring to FIGS. 1, 2, and 4 , the first domain D1 and the seconddomain D2 included in the ferroelectric material may each independentlyinclude at least one crystalline phase selected from an orthorhombiccrystalline phase, a tetragonal crystalline phase, and a cubiccrystalline phase. For example, the first domain D1 and the seconddomain D2 may each independently include an orthorhombic crystallinephase. For example, the first domain D1 and the second domain D2 mayeach independently include an orthorhombic crystalline phase and atetragonal crystalline phase. For example, the first domain D1 and thesecond domain D2 may each independently include an orthorhombiccrystalline phase and a cubic crystalline phase. For example, the firstdomain D1 and the second domain D2 may each independently include anorthorhombic crystalline phase, a tetragonal crystalline phase, and acubic crystalline phase. For example, the ferroelectric material maypredominantly include an orthorhombic crystalline phase. The expression“predominantly including” or “including in plurality” means or refers toa particular crystalline phase is included at the highest content amongall of the crystalline phases or has a two-digit content as apercentage.

The orthorhombic crystalline phase may have, for example, a structurewhich belongs to/has atoms arranged according to a Pca21 space group.The tetragonal crystalline phase may have, for example, a structurewhich belongs to/has atoms arranged according to a P4₂/nmc space group.The cubic crystalline phase may have, for example, a structure whichbelongs to a Fm-3m space group. For example, the ferroelectric materialmay include a tetragonal crystalline phase, which is a structural layerwhich belongs to a Pbcn space group, at the domain wall DW among aplurality of domains including a tetragonal crystalline phase whichbelongs to a P4₂/nmc space group.

A crystal structure, crystalline phase, and atomic arrangement of theferroelectric material may be identified using, for example, one or moreof scanning transmission electron microscopy (STEP), high-angle annulardark-field - scanning transmission electron microscopy (HAADF-STEM),transmission electron microscopy (TEM), or grazing incidence X-raydiffraction (GIXRD). However, example embodiments are not limitedthereto, and any one or more method available in the technical fieldconcerned is applicable.

An amount of the structural layer, which belongs to/is arranged in thePbcn space group, included in the ferroelectric material, may be greaterthan 0 vol% and less than or equal to 40 vol%, greater than 0 vol% andless than or equal to 30 vol%, greater than 0 vol% and less than orequal to 20 vol%, or greater than 0 vol% and less than or equal to 10vol%, with respect to a total volume of the ferroelectric material. Vol%indicates a volume percentage.

The amount of the structural layer which belongs to/is arranged in thePbcn space group may be, for example, greater than 0 mol% and less thanor equal to 40 mol%, greater than 0 mol% and less than or equal to 30mol%, greater than 0 mol% and less than or equal to 20 mol%, or greaterthan 0 mol% and less than or equal to 10 mol%, with respect to the totalnumber of moles of the ferroelectric material. Mol% indicates a molepercentage.

The amount of the structural layer which belongs to/is arranged in thePbcn space group may be, for example, greater than 0 at% and less thanor equal to 40 at%, greater than 0 at% and less than or equal to 30 at%,greater than 0 at% and less than or equal to 20 at%, or greater than 0at% and less than or equal to 10 at%, with respect to the total numberof atoms in the ferroelectric material. At% indicates an atomic percent.

The amount of the structural layer which belongs to/is arranged in thePbcn space group may be, for example, greater than 0 wt% and less thanor equal to 40 wt%, greater than 0 wt% and less than or equal to 30 wt%,greater than 0 wt% and less than or equal to 20 wt%, or greater than 0wt% and less than or equal to 10 wt%, with respect to a total mass ofthe ferroelectric material. Herein, wt% indicates a mass percent.

When the amount of the ferroelectric material is within these ranges,the magnitude of the energy barrier when domain inversion orpolarization direction switching occurs in the ferroelectric materialmay further effectively reduce.

For example, the ferroelectric material may include a binary metal oxiderepresented by Formula 1.

In Formula 1, M is an element which belongs to Group 4 of the periodictable of the elements.

In the binary metal oxide, M may be, for example, Hf, Zr, or acombination of Hf and Zr. The binary metal oxide may be, for example,HfO₂, ZrO₂, or Hf_(1-a)Zr_(a)O₂ (wherein 0≤a≤0.15). When theferroelectric material includes such a binary metal oxide, the magnitudeof the energy barrier when domain inversion or polarization directionswitching occurs may further effectively reduce.

For example, the binary metal oxide may further include a dopant.

When the binary metal oxide further includes a dopant, a structuralstrain may be added to the binary metal oxide. Accordingly, as shown inFIGS. 7A and 7B, in the ferroelectric material including a binary metaloxide, the magnitude of the energy barrier when domain inversion orpolarization direction switching occurs may further reduce.

The dopant included in the binary metal oxide may be, for example, atleast one selected from C, Si, Ge, Sn, Pb, Al, Y, La, Gd, Mg, Ca, Sr Ba,and Ti. An amount of the dopant included in the binary metal oxide maybe, with respect to the entire remainder of atoms other than oxygen,greater than 0 at% and less than or equal to 20 at%, greater than 0 at%and less than or equal to 18 at%, greater than 0 at% and less than orequal to 15 at%, greater than 0 at% and less than or equal to 12 at%,greater than 0 at% and less than or equal to 10 at%, greater than 0 at%and less than or equal to 8 at%, greater than 0 at% and less than orequal to 7 at%, greater than 0 at% and less than or equal to 5 at%,greater than 0 at% and less than or equal to 4 at%, greater than 0 at%and less than or equal to 3 at%, greater than 0 at% and less than orequal to 2 at%, greater than 0 at% and less than or equal to 1 at%,greater than 0 at% and less than or equal to 0.8 at%, greater than 0 at%and less than or equal to 0.5 at%, greater than 0 at% and less than orequal to 0.2 at%, or greater than 0 at% and less than or equal to 0.1at%.

For example, the ferroelectric material may include a binary metal oxiderepresented by Formula 2 or 3.

In Formulae 2 and 3, D may be at least one selected from among C, Si,Ge, Sn, Pb, Al, Y, La, Gd, Mg, Ca, Sr Ba, and Ti, and 0≤x≤0.15, and0≤y≤0.15.

In Formula 2, x may satisfy that, for example, 0≤x≤0.12, 0≤x≤0.1,0≤x≤0.08, 0≤x≤0.07, 0≤x≤0.05, 0≤x≤0.04, 0≤x≤0.03, 0≤x≤0.02 0≤x≤0.01,0≤x≤0.008, 0≤x≤0.005, 0≤x≤0.002, or 0≤x≤0.001. In Formula 3, y maysatisfy that, for example, 0≤y≤0.12, 0≤y≤0.1, 0≤y≤0.08, 0≤y≤0.07,0≤y≤0.05, 0≤y≤0.04, 0≤y≤0.03, 0≤y≤0.02 0≤y≤0.01, 0≤y≤0.008, 0≤y≤0.005,0≤y≤0.002, or 0≤y≤0.001.

According to one or more example embodiments, provided is an electronicdevice including a thin-film dielectric layer, wherein the thin-filmdielectric layer includes the ferroelectric material according to theone or more various example embodiments described above.

As the electronic device includes the ferroelectric material describedabove, the performance of the electronic device, such as the operationspeed, may be improved.

A thickness of the thin-film dielectric layer may be, for example, about0.1 nm to about 50 nm, about 0.1 nm to about 40 nm, about 0.1 nm toabout 30 nm, about 0.1 nm to about 20 nm, about 0.1 nm to about 10 nm,about 0.1 nm to about 7 nm, about 0.1 nm to about 5 nm, about 0.1 nm toabout 4 nm, about 0.1 nm to about 3 nm, about 0.1 nm to about 2 nm,about 0.1 nm to about 1.5 nm, or about 0.1 nm to about 1 nm. When thethin-film dielectric layer has a thickness with these ranges,ferroelectricity may be more effectively provided.

A current versus time profile when polarization switching occurs due toapplication of a voltage to the thin-film dielectric layer may have apeak in a time range of greater than 0 seconds and less than or equal to5 × 10⁻⁷ seconds, greater than 0 and less than or equal to 1 × 10⁻⁷seconds, greater than 0 and less than or equal to 5 × 10⁻⁸ seconds,greater than 0 and less than or equal to 1 × 10⁻⁸ seconds, greater than0 and less than or equal to 5 × 10⁻⁹ seconds, or greater than 0 and lessthan or equal to 1 × 10⁻⁹ seconds. As the current profile according totime when polarization switching occurs by applying a voltage to thethin-film dielectric layer has a peak within these short time ranges, anelectronic device including the thin-film dielectric layer may have afaster driving speed.

The thin-film dielectric layer may be formed by forming an amorphouslayer including a ferroelectric material having a composition ofFormulae 1 to 3 and annealing the amorphous layer to induce acrystalline phase.

The amorphous layer may be formed using a common method. The amorphouslayer may be formed using, for example, one or more of an atomic layerdeposition (ALD), chemical vapor deposition (CVD), physical vapordeposition (PVD), or the like. An ALD method enables forming a uniformlayer at an atomic level and may be performed at a relatively lowtemperature.

When the amorphous layer is formed by the ALD method, common precursorsmay be used for a hafnium source, a zirconium source, and an oxygensource.

For example, the hafnium source may be selected from Hf(OtBu)₄,tetrakis(ethylmethylamino)hafnium (TEMAH),tetrakis(dimethylamino)hafnium (TDMAH), tetrakis(diethylamino)hafnium(TDEAH), or a combination of at least two thereof, but is notnecessarily limited thereto. Any material available as a hafnium sourcemay be used.

For example, the zirconium source may be selected from Zr(OtBu)₄,tetrakis(ethylmethylamino)zirconium (TEMAZ),tetrakis(dimethylamino)zirconium (TDMAZ),tetrakis(diethylamino)zirconium (TDEAZ), or a combination of at leasttwo thereof, but is not necessarily limited thereto. Any materialavailable as a zirconium source may be used.

For example, the oxygen source may be selected from O₃, H₂O, O₂, N₂O, O₂plasma, or a combination of at least two thereof, but is not necessarilylimited thereto. Any material available as an oxygen source may be used.

The amorphous layer may additionally include a dopant. As the amorphouslayer additionally includes a dopant, a strain may be applied to acrystalline phase induced from the amorphous layer. As a result, theenergy barrier when domain inversion occurs in the thin-film dielectriclayer may reduce. For example, a dopant source may be a compoundincluding one or more elements selected from C, Si, Ge, Sn, Pb, Al, Y,La, Gd, Mg, Ca, Sr Ba, and Ti, and any appropriate material availablemay be used. The amount of the dopant may be adjusted according to thephysical properties of the thin-film dielectric layer.

A carbon source may be a hydrocarbon such as one or more of methane,ethane, and/or the like, but is not necessarily limited thereto, and anymaterial available as a carbon source may be used.

A silicon source may be a silane-based compound such as one or more ofSiH₄, Si₂H₆, and the like, but is not necessarily limited thereto, andany material available as a silicon source may be used.

A germanium source may be a germanium-based compound such as one or moreof tetrakis(dimethylamino)germanium (TDMAGe, C₈H₂₄ N₄Ge),bis(N,N′-dimethylethylenediamine)germanium (BDMEDAGe, C₈H₂₀ N₄Ge), orthe like, but is not necessarily limited thereto, and any materialavailable as a germanium source may be used.

A tin source may be a tin-based compound such as one or more of SnCl₂,Sn(SPh)₄, tin(IV) bis(hexamethylsilylamide), or the like, but is notnecessarily limited thereto, and any material available as a tin sourcemay be used.

A lead source may be a lead-based compound such as one or more ofPb(Ac)₂ (Ac=acetate), PbCl₂, or the like, but is not necessarily limitedthereto, and any material available as a lead source may be used.

An aluminum source may be an aluminum-based compound such as one or moreof trimethoxyaluminum (TMA), dimethylaluminum chloride (DMACI), or thelike, but is not necessarily limited thereto, and any material availableas an aluminum source be used.

An yttrium source may be an yttrium-based compound such as one or moreof Y(thd)₃ (thd = 2,2,6,6-tetramethyl-3,5-heptanedionato), Y(CH₃Cp)₃ (Cp= cyclopentadienyl), or the like, but is not necessarily limitedthereto, and any material available as a yttrium source may be used.

A lanthanum source may be a lanthanum-based compound such as one or moreof La(thd)₃ (thd = 2,2,6,6-tetramethyl-3,5-heptane-dione), La(Cp)s (Cp =cyclopentadienyl), or the like, but is not necessarily limited thereto,and any material available as a lanthanum source be used.

A gadolinium source may be a gadolinium -based compound such as one ormore of Gd(thd)₃, Gd(DPDMG)₃ (DPDMG =N,N-diisopropyl-2-dimethylamido-guanidinato), or the like, but is notnecessarily limited thereto, and any material available as a gadoliniumsource may be used.

A magnesium source may be a magnesium-based compound such as one or moreof Mg(thd)₂, MgCl₂, or Mg(NO₃)₂, but is not necessarily limited thereto,but is not necessarily limited thereto, and any material available as amagnesium source may be used.

A calcium source may be a calcium-based compound such as one or more of(α-methylstyrene)Cu(l)(hfac) (hfac = hexafluoroacetylacetonate),(hfac)Cu(I)DMB (DMB = 3,3-dimethyl-1-butene), or the like, but is notnecessarily limited thereto, and any material available as a calciumsource may be used.

A strontium source may be a strontium-based compound such as one or moreof Sr(tmhd)2 (tmhd = 2,2,6,6-tetramethyl-3.5-heptanedione), Sr(iPrCp)₂(iPr = isopropyl, Cp = cyclopentadienyl), or the like, but is notnecessarily limited thereto, and any material available as a strontiumsource may be used.

A barium source may be a barium-based compound such as Ba(CpiPr₃)₂ (Bis(triisopropylcyclopentadienyl)barium), Ba(TMHD)₂(Bis(2,2,6,6-tetramethyl-3,5-heptanedionato)barium hydrate), but is notnecessarily limited thereto, and any material available as a bariumsource may be used.

A titanium source may be a titanium-based compound such as TiCl₄,TTIP(CsH₂₄ N₄Ti), trimethoxy(pentamethylcyclopentadienyl)titanium((CpMe₅)Ti(OMe)₃), or the like, but is not necessarily limited thereto,and any material available as a titanium source may be used.

The annealing may be controlled in temperature, time, atmosphere, andthe like so that the amorphous layer is crystallized to have acrystalline structure, for example, an orthorhombic crystallinestructure. A thermal budget of the annealing may be determined inconsideration of the composition, thickness, and the like of theamorphous layer. The annealing may be performed at a temperature of, forexample, about 400° C. to about 1100° C., but is not necessarily limitedto this temperature range, and may be controlled according to physicalproperties required. The annealing may be performed for, for example,about 1 nanosecond to about 1 hour, about 1 microsecond to about 30minutes, about 0.001 seconds to about 10 minutes, about 0.01 second toabout 10 minutes, about 0.05 seconds to about 5 minutes, about 0.1second to about 3 minutes, about 0.5 seconds to about 2 minutes, about 1second to about 1 minutes, about 3 seconds to about 1 minute, or about 5seconds to about 30 seconds, but is not necessarily limited to theseranges, and may be controlled according to physical properties required.The annealing may be performed at least one time. The annealing may beperformed, for example, multiple times. The annealing may include, forexample, first annealing and second annealing. The first annealing andthe second annealing may be the same, or may be different in terms of atleast one of the annealing temperature and the annealing time. Forexample, the first annealing may be performed at a lower temperature orfor a shorter period of time than the second annealing. The atmospherein which the annealing is performed is not particularly limited. Forexample, the first annealing and the second annealing may each beperformed under an atmosphere of H₂O, O₂, O₃, N₂, H₂, and/or NH₃.

In some example embodiments, the thin-film dielectric layer may beformed, for example, by forming on a substrate a crystalline layerincluding a ferroelectric material having a composition of Formulae 1 to3. For example, the crystalline layer may be formed using a method suchas epitaxy, liquid phase epitaxy, vapor phase epitaxy, chemical vapordeposition (CVD), sputtering, pulsed laser deposition (PLD), or thelike.

For example, the electronic device may further include a thin-filmelectrode layer, and the thin-film electrode layer may be arranged onone surface or both surfaces of the thin-film dielectric layer.

For example, the electronic device may include: a thin-film dielectriclayer including the ferroelectric material described above; and athin-film electrode layer arranged on one surface or both surfaces ofthe thin-film dielectric layer.

A thickness of the thin-film electrode layer may be, for example, about10 nm to about 1000 nm, about 10 nm to about 500 nm, or about 10 nm toabout 100 nm.

The thin-film electrode layer included in the electronic device may be,for example, amorphous or crystalline. The crystalline thin-filmelectrode layer may have various crystalline structures. The thin filmelectrode layer may have, for example, a tetragonal structure, a cubicstructure, a hexagonal structure, a monoclinic structure, a triclinicstructure, or an orthorhombic structure. As the thin-film electrodelayer has such a crystalline structure, interfacial stability with thethin-film dielectric layer may be improved.

At least one thin-film electrode layer may include at least one selectedfrom a metal, an oxide of the metal, a doped oxide of the metal, anitride of the metal, and a carbide of the metal.

The metal included in at least one thin-film electrode layer mayinclude, for example, at least one selected from Ti, W, Ta, Co, Mo, Ni,V, Hf, Al, Cu, Pt, Pd, Ir, Au, and Ru. The metal included in at leastone thin-film electrode layer is not limited thereto, and any metal usedfor an electrode layer may be used.

The metal oxide(oxide of the metal) included in at least one thin-filmelectrode layer may include, for example, at least one selected fromRuO₂, IrO₂, PtO₂, SnO₂, MnO₂, Sb₂O₃, and In₂O₃. The metal oxide includedin at least one thin-film electrode layer is not limited thereto, andany metal oxide used in an electrode layer may be used.

The doped metal oxide (doped oxide of the metal) included in at leastone thin-film electrode layer may include, for example, at least oneselected from Ta-doped SnO₂, Ti-doped In₂O₃, Ni-doped SnO₂, Sb-dopedSnO₂, and Al-doped ZnO. The doped metal oxide included in at least onethin-film electrode layer is not limited thereto, and any doped metaloxide used in an electrode layer may be used. The type of a dopant ofthe doped metal oxide is not specifically limited, and any dopant, forexample any dopant that improves conductivity of metal oxide ispossible. The dopant may be, for example, a metal.

The metal nitride (nitride of the metal) included in at least onethin-film electrode layer may include, for example, at least oneselected from TiN, WN, TaN, TiAIN, TaSiN, TiSiN, WSiN, TiCN, TiAICN,RuCN, and RuTiN. The metal nitride included in at least one thin-filmelectrode layer is not limited thereto, and any metal nitride used foran electrode layer may be used. The metal nitride may include acarbon-containing nitride of a metal.

As the electronic device additionally includes the thin-film electrodelayer, the electronic device may be used for various purposes. Theelectronic device may be or may include, for example, a capacitor, atransistor, a memory unit, and/or the like. The electronic device maybe, for example, a semiconductor device such as a memory device, anon-memory device such as a logic device, or the like. The semiconductordevice may be, for example, a capacitor, a field-effect transistor(FET), or a combined structure of a capacitor and a FET, but is notlimited thereto.

For example, the electronic device may further include: a semiconductorsubstrate including a source and a drain; and a gate electrode arrangedon the semiconductor substrate, wherein the thin-film dielectric layermay be arranged between the semiconductor substrate and the gateelectrode.

For example, the electronic device may include: a semiconductorsubstrate including a source and a drain; a gate electrode arranged onthe semiconductor substrate; and a thin-film dielectric layer arrangedbetween the semiconductor substrate and the gate electrode.

FIGS. 8 and 9 are schematic views showing field-effect transistors(FETs) according to embodiments.

Referring to FIGS. 8 and 9 , each FET D10 (D20) includes: a substrateincluding a source 120 (121) and a drain 130 (131); a gate electrode 300arranged on the substrate 100; and a first thin-film dielectric layer200 which is arranged between the substrate 100 and the gate electrode300 and includes the ferroelectric material according to the one or moreembodiments described above. The FETs D10 and D20 may be or may includeor correspond to or be included in logic switching devices. Logicswitching devices, having a concept in contrast to memory devices(memory transistors), may have non-memory properties, and may benon-memory ON/OFF switching devices.

The substrate 100 may include a semiconductor material. For example, thesubstrate 100 may include Si, Ge, SiGe, a Group III-V semiconductor, orthe like, and may be modified and used in various forms such as asilicon on insulator (SOI).

The substrate 100 may include the source 120 (121) and the drain 130(131), and may include a channel 110 (111) electrically connected to thesource 120 (121) and the drain 130 (131). The source 120 (121) may beelectrically connected to or contact one end of the channel 110 (111),and the drain 130 (131) may be electrically connected or may contact theother end of the channel 110 (111).

Referring to FIG. 8 , the channel 110 may be defined as a substrateregion between the source 120 and the drain 130 in the substrate 100.The source 120 and the drain 130 may be formed by implanting impuritiesinto different regions of the substrate 100. In this case, the source120, the channel 110, and the drain 130 may include a substrate materialas a base material.

The electronic device may further include an insulating layer arrangedbetween the thin-film dielectric layer and the semiconductor substrate.

Referring to FIG. 9 , the channel 111 may be implemented as a thin-filmmaterial layer separate from a substrate region 101. A materialconstituting the channel 111 may be selected according to requiredphysical properties of the electronic device. For example, the channel111 may include a material selected from: semiconductor materials suchas Si, Ge, SiGe, Group III-V, or the like; an oxide semiconductor; anitride semiconductor; an oxynitride semiconductor; a two-dimensional(2D) material; a quantum dot (QD), an organic semiconductor; andcombinations of at least two thereof. For example, the oxidesemiconductor may include, for example, InGaZnO or the like. The 2Dmaterial may include transition metal dichalcogenide (TMD) or graphene.The quantum dot may include a colloidal QD, a nanocrystal structure, orthe like. The source 121 and the drain 131 may include a conductivematerial, and, for example, may each independently include a metal, ametal-containing compound, or a conductive polymer.

Referring to FIGS. 8 and 9 , the gate electrode 300 may be arranged overthe substrate 100 and spaced apart from the substrate 100, and may bearranged opposite to the channel 110 (111). The gate electrode 300 mayhave a conductivity greater than 0 and less than or equal to1mohm/square or less. The gate electrode 300 may include at least oneselected from the group consisting of or including a metal, a metalnitride, a metal carbide, a polysilicon, and combinations thereof. Themetal may include, for example, aluminum (Al), tungsten (W), molybdenum(Mo), titanium (Ti), or tantalum (Ta). The metal nitride may include,for example, titanium nitride (TiN) or tantalum nitride (TaN). The metalcarbide may include, for example, aluminum- or silicon-doped (oraluminum- or silicon-containing) metal carbide. The metal carbide mayinclude, for example, TiAIC, TaAIC, TiSiC, or TaSiC. The gate electrode300 may have a structure in which a plurality of material layers arestacked. For example, the gate electrode 300 may have a stack structureof a metal nitride layer/metal layer, such as TiN/Al, or a stackstructure of a metal nitride layer/metal carbide layer/metal layer, suchas TiN/TiAIC/W. For example, the gate electrode 300 may include atitanium nitride film (TiN) or molybdenum (Mo). The embodimentsdescribed above may be used in various modifications. The firstdielectric layer thin film 200 including the ferroelectric materialdescribed above may be arranged between the substrate 100 and the gateelectrode 300. For example, the first dielectric layer thin film 200including the ferroelectric material described above may be formed onthe channel 110 (111).

FIG. 10 is a schematic view showing a semiconductor device D30 accordingto some example embodiments.

Referring to FIG. 10 , a second dielectric layer 400 may be furtherincluded between the channel 110 and the first dielectric layer thinfilm 200 including the ferroelectric material. The second dielectriclayer 400 may suppress or prevent electrical leakage. A thickness of thesecond dielectric layer 400 may be, for example, about 0.1 nm to about100 nm, about 0.1 nm to about 50 nm, about 0.1 nm to about 30 nm, about0.5 nm to about 10 nm, about 1 nm to about 5 nm, about 1 nm to about 4nm, about 1 nm to about 3 nm, or about 1 nm to about 2 nm. The seconddielectric layer 400 may include a paraelectric material or ahigh-dielectric material. The second dielectric layer 400 may include,for example, silicon oxide, silicon nitride, aluminum oxide, hafniumoxide, zirconium oxide, or the like. The second dielectric layer 400 mayinclude, for example, a two-dimensional (2D) insulator such as hexagonalboron nitride (h-BN). For example, the second dielectric layer 400 mayinclude silicon oxide (SiO₂), silicon nitride (SiN_(x)), or the like.The second dielectric layer 400 may include, for example, one or more ofhafnium oxide (HfO₂), hafnium silicon oxide (HfSiO₄), lanthanum oxide(La₂Os), lanthanum aluminum oxide (LaAlO₃), zirconium oxide (ZrO₂),zirconium silicon oxide (ZrSiO₄), tantalum oxide(Ta₂O₅), titanium oxide(TiO₂), strontium titanium oxide(SrTiO₃), yttrium oxide (Y₂O₃), aluminumoxide (Al₂O₃), red scandium tantalum oxide (PbSc_(0.5)Ta_(0.5)O₃), redzinc niobate (PbZnNbOs), or the like. The second dielectric layer 400may include, for example, a metal oxynitride such as aluminum oxynitride(AION), zirconium oxynitride (ZrON), hafnium oxynitride (HfON),lanthanum oxynitride (LaON), yttrium oxynitride (YON), or the like. Thesecond dielectric layer 400 may include, for example, a silicate such asZrSiON, HfSiON, YsiON, LaSiON, or the like. The second dielectric layer400 may include, for example, an aluminate such as one or more ofZrAION, HfAlON, or the like.

Referring to FIG. 10 , a conductive layer 500 may be further arrangedbetween the channel 110 and the first dielectric layer thin film 200including the ferroelectric material. The conductive layer 500 may havea conductivity greater than 0 and less than or equal to 1 mohm/square.The conductive layer 500 may be, for example, a floating electrode. Theconductive layer 500 may be formed of, for example, a metal or ametal-containing compound.

The semiconductor device may be implemented as a field-effect transistor(FET) in various forms, such as a two-dimensional or three-dimensionalform. For example, the FET may have: a 1-gate on channel form, like aplanar-FET; a 3-gate on channel form, like a Fin-FET; or a 4-gate onchannel form, like a gate-all-around-FET.

FIG. 11 is a schematic view showing a structure of a Fin-FET as asemiconductor device according to another embodiment.

Referring to FIG. 11 , the Fin-FET D40 may include a source 120, a drain130, and a channel (not shown) defined between the source S and thedrain D, and the channel may have a fin shape. The gate electrode 300may be arranged on a substrate including a fin shape, to cross the finshape. The channel may be formed in a region in which the fin shape andthe gate electrode 300 cross each other. The first dielectric layer thinfilm 200 including the ferroelectric material is arranged between thechannel and the gate electrode 300 while surrounding the channel andcontacting the source 120 and the drain 130.

FIG. 12 is a schematic view showing a structure of a gate-all-around-FETas a semiconductor device according to another embodiment.

Referring to FIG. 12 , a gate-all-around-FET D50 may include a source120, a drain 130, and a channel (not shown) defined as a regiontherebetween, and the channel may have a form of wire, sheet, or thelike. The source 120, the drain 130, and the channel may be arranged tobe spaced apart from a substrate region 101. A gate electrode 300 may bearranged to cross and surround the source 120, the drain 130, and thechannel. The channel may be formed in a region surrounded by the gateelectrode 300. The first dielectric layer thin film 200 including theferroelectric material may be arranged between the channel and the gateelectrode 300 to surround the channel. The gate-all-around-FET D50 maybe a multi-bridge channel FET (MBCFET™); however, example embodimentsare not limited thereto.

For example, the electronic device may be a capacitor including: athin-film dielectric layer including the ferroelectric materialdescribed above; and a thin-film electrode layer arranged on bothsurfaces of the thin-film dielectric layer.

FIG. 13 is a schematic view showing a capacitor according to someexample embodiments.

Referring to FIG. 13 , a capacitor D60 may include a first electrode600, a second electrode 700 arranged to face and be spaced apart fromthe first electrode 600, and the first dielectric layer thin film 200which includes the ferroelectric material and is arranged between thefirst electrode 600 and the second electrode 700. The first electrode600 and the second electrode 700 may be referred to as a lower electrodeand an upper electrode, respectively.

The first electrode 600 and the second electrode 700 may have aconductivity of greater than 0 and less than or equal to 1 mohm/square.The first electrode and the second electrode may consist of or mayinclude the same material or different materials. The first electrode600 and the second electrode 700 may each independently include ortogether include one or more of TiN, TaN, Ti, Ta, TiCN, TiSiN, WSiN,TiAlN, TaAlN, TiAlCN, TiW, RuTiN, RuCN, Pt, Au, Mo, or Al. The firstelectrode 600 and the second electrode 700 may each independentlyinclude TiN or Mo. The first electrode 600 and the second electrode 700may each independently or together have a thickness of about 1 nm toabout 20 nm.

For example, the electronic device may include: a semiconductorsubstrate including a source and a drain; a gate electrode arranged onthe semiconductor substrate; and the first dielectric layer thin filmarranged between the semiconductor substrate and the gate electrode, andmay further include a capacitor. The capacitor may further include: thefirst dielectric layer thin film described above; and a first thin-filmelectrode layer and a second thin-film electrode layer which arearranged on both surfaces of the first dielectric layer thin film,respectively, and the capacitor may be arranged on or buried in thesemiconductor substrate.

The electronic device may be, for example, a semiconductor device. Thesemiconductor device may have a form in which a plurality ofsemiconductor devices are connected. For example, the semiconductordevice may have a form in which an FET and a capacitor are electricallyconnected. For example, the semiconductor device may have memoryproperties, and may be, for example, a DRAM.

FIG. 14 is a schematic view showing a structure of a semiconductordevice according to various example embodiments, e.g., a connectionstructure of a capacitor and an FET.

Referring to FIG. 14 , a semiconductor device D70 has a structure inwhich the capacitor D60, which includes the first dielectric layer thinfilm 200 including the ferroelectric material described above, and a FETD61 are electrically connected by a contact 62. One of the first andsecond electrodes 600 and 700 of the capacitor D60 is electricallyconnected to one of a source 120 and a drain 130 of the FET D61 by thecontact 62. The contact 62 may include an appropriate conductivematerial, for example, one or more of tungsten, copper, aluminum,polysilicon, or the like.

The FET D61 may include: a substrate 100 including the source 120, thedrain 130, and a channel 110; and the gate electrode 300 arranged toface the channel 110. A second dielectric layer 410 may be furtherincluded between the substrate 100 and the gate electrode 300. Althoughthe FET D61 of FIG. 12 is illustrated as an example which does notinclude the second dielectric layer thin film 200 including theferroelectric material, the FET D61 may include the second dielectriclayer thin film 200 including the ferroelectric material. For the source120, the drain 130, the channel 110, the substrate 100, and the gateelectrode 300, the description of the transistor (FET) provided abovemay be referred to. For the second dielectric layer 410, the descriptionof the second dielectric layer 400 provided above may be referred to.Although not illustrated, the positions of the capacitor D60 and the FETD61 may be variously changed. For example, the capacitor D60 may bearranged on the substrate 100 or may be buried in the substrate 100.

FIG. 15 is a schematic cross-sectional view illustrating a structure ofan electronic device 300 according to some example embodiments.Referring to FIG. 15 , the electronic device 300 includes a substrate201, a first source/drain region 202 protruding in the Z-direction froman upper surface of the substrate 201, a second source/drain region 203protruding in the Z-direction from the upper surface of the substrate201, a channel 204 separated from the upper surface of the substrate 201and having a bar shape extending in the Y-direction, an interfacialinsulating layer 205 surrounding and covering the channel 204, aferroelectric layer 206 surrounding and covering the interfacialinsulating layer 205, and a gate electrode 207 surrounding and coveringthe ferroelectric layer 206. The ferroelectric layer 206 may be aferroelectric thin film structure 150 or 154 which are included in theabove described electronic device 100, 101, 102, 103, 104 or 015. Thechannel 204 may include a plurality of channel elements 204 a, 204 b,204 c disposed at a distance from each other in the Z-direction or an Xdirection that is different from the Y-direction. In FIG. 15 , althoughthe three channel elements 204 a, 204 b, and 204 c are illustrated asbeing separated from each other in the Z-direction, this is merely anexample and is not necessarily limited thereto. The electronic device300 illustrated in FIG. 15 may be, for example, a GAAFET or an MBCFET™.

FIG. 16 is a schematic cross-sectional view showing a gate structure ofthe electronic device 300 shown in FIG. 15 , and in particular, across-sectional view taken along line C-C' of the gate structure.Referring to FIG. 16 , the semiconductor device 300 may include aplurality of interfacial insulating layers 205 disposed to respectivelysurround four surfaces of the plurality of channel elements 204 a, 204b, and 204 c. Also, the electronic device 300 may include a plurality offerroelectric layers 206 disposed to respectively surround four surfacesof the plurality of interfacial insulating layers 205. The gateelectrode 207 may have a structure extending in the Z-direction byprotruding from an upper surface of the substrate 201 to surround foursurfaces of each of the plurality of ferroelectric layers 206.

FIG. 17 is a schematic view of an electronic device according to someexample embodiments.

Referring to FIG. 17 , an electronic device 500 may have a stackstructure 502 in which a plurality of insulating layers 560 and aplurality of gate electrodes 510 are alternately and repeatedly stacked,and the ferroelectric layer 530, the interfacial layer 540, the channel550, and the dielectric filler 520 may be arranged to penetrate thestack structure 502. The ferroelectric layer 530 may be a ferroelectricthin film structure 150 or 154 which are included in the above describedelectronic device 100, 101, 102, 103, 104 or 015. In detail, theinsulating layers 560 and the gate electrodes 510 each may extend on thesubstrate 501 along an X-Y plane, and the insulating layers 560 and thegate electrodes 510 are alternately and repeatedly stacked in the Zdirection (e.g., vertical direction), thereby forming the stackstructure 502. Furthermore, the electronic device 500 may include a cellstring 503 that includes the ferroelectric layer 530, the interfaciallayer 540, the channel 550, and the dielectric filler 520, and the cellstring 503 may be arranged to penetrate the stack structure 502 (e.g.,in the Z direction, or vertical direction). In other words, theinsulating layers 560 and the gate electrodes 510 may be arranged tosurround the periphery of the cell string 503. In detail, theferroelectric layer 530, the interfacial layer 540, the channel 550, andthe dielectric filler 520 all may extend in the Z direction through thestack structure to intersect the insulating layers 560 and the gateelectrodes 510. Furthermore, the dielectric filler 520 may be arrangedin the center of the cell string 503, and the ferroelectric layer 530,the interfacial layer 540, and the channel 550 may be arranged tosurround (e.g., concentrically surround as shown in FIG. 17 ) thedielectric filler 520. The interfacial layer 540 may be arranged betweenthe ferroelectric layer 530 and the channel 550. The interfacial layer540 may be an insulating layer. The electronic device 500 may include aplurality of cell strings as the cell string 503, and the cell strings503 may be arranged spaced apart from each other (e.g., isolated fromdirect contact with each other) on the X-Y plane (e.g., plane of thestack structure) in a two dimension (e.g., along a plane of the stackstructure as shown in FIG. 17 , wherein the vertical direction or Zdirection is perpendicular to the plane of the stack structure, or X-Yplane).

FIG. 18 is a block diagram schematically illustrating an electronicdevice 3000 according to some example embodiments.

Referring to FIG. 18 , the electronic device 3000 according to someexample embodiments may include a PDA, a laptop computer, a portablecomputer, a web tablet, a wireless phone, a mobile phone, a digitalmusic player, a wired/wireless electronic device, or a compositeelectronic device including at least two of the devices described above.The electronic device 3000 may include at least one of a controller 320,an input/output device 330, such as a keypad, a keyboard, and a display,a memory 340, and a wireless interface 350 combined to each otherthrough a bus 310, and may include at least one active or passivecircuit component.

Any one or more of the components illustrated in FIG. 18 may include aferroelectric material, such as the ferroelectric materials describedabove with reference to FIGS. 1-7 . For example, any one or more of thecomponents illustrated in FIG. 18 may include the ferroelectric materialimplemented as one or more of the transistors D10-D50 and/or capacitorD6 and/or semiconductor device D70 illustrated above. Any one or more ofthe components illustrated in FIG. 18 may also include one or moreactive or passive component.

The controller 320 may include, for example, one or moremicroprocessors, digital signal processors, microcontrollers, or thelike. The memory 340 may be used, for example, to store instructions tobe executed by controller 320.

The memory 340 may be used to store user data. The memory 340 mayinclude a magnetic tunneling junction device, and may include anonvolatile memory device.

The electronic device 3000 may use the wireless interface 350 totransmit data to or receive data from a wireless communication networkthat communicates with an RF signal. For example, the air interface 350may include at least one of an antenna, a wireless transceiver, and thelike. The electronic device 3000 may be used in a communicationinterface protocol like a 3G communication system, such as at least oneof a Code-division multiple access (CDMA), Global System for Mobiles(GSM), north American digital cellular (NADC), Enhanced-time-divisionmultiple-access (E-TDMA), Wideband Code Division Multiple Access(WCDAM), or CDMA2000.

Any of the elements and/or functional blocks disclosed above may includeor be implemented in processing circuitry such as hardware includinglogic circuits; a hardware/software combination such as a processorexecuting software; or a combination thereof. For example, theprocessing circuitry more specifically may include, but is not limitedto, a central processing unit (CPU), an arithmetic logic unit (ALU), adigital signal processor, a microcomputer, a field programmable gatearray (FPGA), a System-on-Chip (SoC), a programmable logic unit, amicroprocessor, application-specific integrated circuit (ASIC), etc. Theprocessing circuitry may include electrical components such as at leastone of transistors, resistors, capacitors, etc. The processing circuitrymay include electrical components such as logic gates including at leastone of AND gates, OR gates, NAND gates, NOT gates, etc.

As described above, according to the one or more example embodiments, aferroelectric material includes a structural layer having a novelsymmetric structure at the domain wall, and thus, the energy barrierwhen domain inversion occurs in the ferroelectric material may reduce.

It should be understood that various example embodiments describedherein should be considered in a descriptive sense only and not forpurposes of limitation. Descriptions of features or aspects withinvarious example embodiments should typically be considered as availablefor other similar features or aspects in other embodiments; for example,example embodiments are not necessarily mutually exclusive. While one ormore embodiments have been described with reference to the figures, itwill be understood by those of ordinary skill in the art that variouschanges in form and details may be made therein without departing fromthe spirit and scope as defined by the following claims.

What is claimed is:
 1. A ferroelectric material comprising: a firstdomain including a first polarization layer configured to be polarizedin a first direction and a first spacer layer adjacent to the firstpolarization layer; a second domain including a second polarizationlayer configured to be polarized in a second direction distinct from thefirst direction and a second spacer layer adjacent to the secondpolarization layer; and a structural layer at a domain wall between thefirst domain and the second domain, the structural layer arranged as aPbcn space group.
 2. The ferroelectric material of claim 1, wherein thestructural layer has an orthorhombic crystal structure.
 3. Theferroelectric material of claim 1, wherein the structural layercomprises at least a portion of the first polarization layer and atleast a portion of the second polarization layer.
 4. The ferroelectricmaterial of claim 3, wherein the first spacer layer and the secondspacer layer are not present between the first polarization layer andthe second polarization layer in the structural layer.
 5. Theferroelectric material of claim 1, wherein the ferroelectric materialincludes a compound having a fluorite structure.
 6. The ferroelectricmaterial of claim 1, wherein the first polarization layer includes fouroxygen atoms and two metal atoms, and the four oxygen atoms and the twometal atoms have non-symmetry in a polar C-axis direction, and the firstdirection is one of two directions parallel to the polar C-axisdirection.
 7. The ferroelectric material of claim 1, wherein the secondpolarization layer includes four oxygen atoms and two metal atoms, andthe four oxygen atoms and the two metal atoms have non-symmetry in apolar C-axis direction, and the second direction is a direction oppositeto the first direction which is one of two directions parallel to thepolar C-axis direction.
 8. The ferroelectric material of claim 1,wherein the first spacer layer is a non-polarizable layer, the spacerlayer includes four oxygen atoms and two metal atoms, and the fouroxygen atoms and the two metal atoms have symmetry in a polar C-axisdirection.
 9. The ferroelectric material of claim 1, wherein the firstdomain comprises a plurality of first polarization layers and aplurality of first spacer layers between the plurality of firstpolarization layers, and the second domain comprises a plurality ofsecond polarization layers and a plurality of second spacer layersdisposed between the plurality of second polarization layers.
 10. Theferroelectric material of claim 9, wherein the plurality of firstpolarization layers included in the first domain are configured to bepolarized in the first direction, and the plurality of secondpolarization layers included in the second domain are configured to bepolarized in the second direction.
 11. The ferroelectric material ofclaim 1, wherein the first polarization layer and the secondpolarization layer have a same chirality.
 12. The ferroelectric materialof claim 1, wherein a strain applied to the structural layer is about-1% to about 1%.
 13. The ferroelectric material of claim 1, wherein thefirst domain and the second domain each independently include at leastone crystalline phase selected from an orthorhombic crystalline phase, atetragonal crystalline phase, and a cubic crystalline phase.
 14. Theferroelectric material of claim 13, wherein the orthorhombic crystallinephase is arranged as a Pca21 space group, the tetragonal crystallinephase is arranged as a P4₂/nmc space group, and the cubic crystallinephase is arranged as a Fm-3m space group.
 15. The ferroelectric materialof claim 1, wherein an amount of the structural layer is greater than 0vol% and less than or equal to about 40 vol% with respect to a totalvolume of the ferroelectric material.
 16. The ferroelectric material ofclaim 1, wherein the ferroelectric material comprises a binary metaloxide represented by Formula 1: <Formula 1> MO₂ wherein, in Formula 1, Mis an element which belongs to Group IV of the periodic table of theelements.
 17. The ferroelectric material of claim 16, wherein M is Hf orZr.
 18. The ferroelectric material of claim 16, wherein the binary metaloxide comprises a dopant.
 19. The ferroelectric material of claim 18,wherein the dopant is at least one selected from C, Si, Ge, Sn, Pb, Al,Y, La, Gd, Mg, Ca, Sr Ba, and Ti.
 20. The ferroelectric material ofclaim 1, wherein the ferroelectric material comprises a binary metaloxide represented by Formula 2 or 3: <Formula 2> Hf₁-_(x)D_(x)O₂<Formula 3> Zr_(1-x)D_(x)O₂ wherein, in Formulae 2 and 3, D is at leastone selected from C, Si, Ge, Sn, Pb, Al, Y, La, Gd, Mg, Ca, Sr Ba, andTi, and 0≤x≤0.15.
 21. An electronic device comprising a thin-filmdielectric layer, wherein the thin-film dielectric layer comprises theferroelectric material according to claim
 1. 22. The electronic deviceof claim 21, wherein the thin-film dielectric layer has a thickness ofabout 0.1 nm to about 50 nm.
 23. The electronic device of claim 21,wherein a current versus time profile in response to polarizationswitching occurring due to application of a voltage to the thin-filmdielectric layer has a peak in a range of greater than 0 and less thanor equal to 5 × 10⁻⁷ sec.
 24. The electronic device of claim 21, furthercomprising: a thin-film electrode layer, wherein the thin-filmdielectric layer is arranged on a surface or both surfaces of thethin-film electrode layer.
 25. The electronic device of claim 24,wherein the thin-film electrode layer has a thickness of about 10 nm toabout 1000 nm.
 26. The electronic device of claim 24, wherein thethin-film electrode layer comprises at least one selected from a metal,an oxide of the metal, a doped oxide of the metal, a nitride of themetal, and a carbide of the metal.
 27. The electronic device of claim26, wherein a metal included in the thin-film electrode layer comprisesat least one selected from Ti, W, Ta, Co, Mo, Ni, V, Hf, Al, Cu, Pt, Pd,Ir, Au, and Ru, the oxide of the metal comprises at least one selectedfrom RuO₂, IrO₂, PtO₂, MnO₂, Sb₂O₃, and ln₂O₃, the doped oxide of themetal comprises at least one selected from a Ta-doped SnO₂, a Ti-dopedln₂O₃, a Ni-doped SnO₂, a Sb-doped SnO₂, and an Al-doped ZnO, and thenitride of the metal comprises at least one selected from TiN, WN, TaN,TiAIN, TaSiN, TiSiN, WSiN, TiCN, TiAICN, RuCN, and RuTiN.
 28. Theelectronic device of claim 21, wherein the electronic device is at leastone of a capacitor, a transistor, or a memory cell.
 29. The electronicdevice of claim 21, further comprising: a semiconductor substrateincluding a source and a domain; and a gate electrode arranged on thesemiconductor substrate, wherein the thin-film dielectric layer isbetween the semiconductor substrate and the gate electrode.
 30. Theelectronic device of claim 29, further comprising: an insulating layerarranged between the thin-film dielectric layer and the semiconductorsubstrate.
 31. The electronic device of claim 29, further comprising acapacitor, wherein the capacitor comprises: the thin-film dielectriclayer; and a first thin-film electrode layer and a second thin-filmelectrode layer on both surfaces of the thin-film dielectric layer,respectively, and the capacitor is on the semiconductor substrate or isburied in the semiconductor substrate.
 32. A ferroelectric materialcomprising: a first domain including a first polarization layerconfigured to be polarized in a first direction and a spacer layeradjacent to the first polarization layer; and a structural layer at adomain wall between the first domain and a second domain, the structurallayer having metal atoms and oxygen atoms, the metal atoms and theoxygen atoms arranged as a Pbcn space group.
 33. The ferroelectricmaterial of claim 32, wherein the oxygen atoms included in a unit cellof the structural layer are symmetric with respect to a polar C-axisdirection.
 34. The ferroelectric material of claim 32, wherein otheroxygen atoms included in a unit cell of the first polarization layer arenot symmetric with respect to a polar C-axis direction.
 35. Anelectronic device including: at least one active or passive element; andthe ferroelectric material of claim
 32. 36. The electronic device ofclaim 35, wherein the ferroelectric material is included in at least oneof a capacitor or a transistor.